code: def testBasic(self):
      for shape in [(), (3,), (3, 4, 4)]:
          filt = MeanStdFilter(shape)
          for i in range(5):
              filt(np.ones(shape))
          self.assertEqual(filt.running_stats.n, 5)
          self.assertEqual(filt.buffer.n, 5)
  
          filt2 = MeanStdFilter(shape)
          filt2.sync(filt)
          self.assertEqual(filt2.running_stats.n, 5)
          self.assertEqual(filt2.buffer.n, 5)
  
          filt.reset_buffer()
          self.assertEqual(filt.buffer.n, 0)
          self.assertEqual(filt2.buffer.n, 5)
  
          filt.apply_changes(filt2, with_buffer=False)
          self.assertEqual(filt.buffer.n, 0)
          self.assertEqual(filt.running_stats.n, 10)
  
          filt.apply_changes(filt2, with_buffer=True)
          self.assertEqual(filt.buffer.n, 5)
          self.assertEqual(filt.running_stats.n, 15)
  
file_path: ray/rllib/tests/test_filters.py
imports: import numpy
  import unittest
  import ray
  from ray.rllib.utils.filter import RunningStat, MeanStdFilter
  from ray.rllib.utils import FilterManager
  from ray.rllib.tests.mock_worker import _MockWorkerSet
label_desc: Use image node_id 1 for calling the MeanStdFilterTest obj's underlying member method code with example usage: obj.testBasic() without return types